US3760214A - Shadow masks for use in colour picture tubes - Google Patents

Shadow masks for use in colour picture tubes Download PDF

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Publication number
US3760214A
US3760214A US00214551A US3760214DA US3760214A US 3760214 A US3760214 A US 3760214A US 00214551 A US00214551 A US 00214551A US 3760214D A US3760214D A US 3760214DA US 3760214 A US3760214 A US 3760214A
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US
United States
Prior art keywords
shadow mask
electron beam
electron
colour picture
shaped section
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00214551A
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English (en)
Inventor
E Yamazaki
H Kanai
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Ltd
Original Assignee
Hitachi Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
Application granted granted Critical
Publication of US3760214A publication Critical patent/US3760214A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/06—Screens for shielding; Masks interposed in the electron stream
    • H01J29/07—Shadow masks for colour television tubes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2229/00—Details of cathode ray tubes or electron beam tubes
    • H01J2229/07—Shadow masks
    • H01J2229/0727—Aperture plate
    • H01J2229/0777—Coatings

Definitions

  • This invention relates to an improved shadow mask for use in a colour picture tube, more particularly a colour receiving tube of the post focusing type.
  • post focusing system For the purpose of increasing the brightness of the fluorescent screen of a colour picture tube and for improving the colour purity so-called post focusing system has been proposed wherein an electron lens is disposed near a shadow mask for restricting the diameter of the electron beam which has passed through the shadow mask.
  • a conventional shadow mask comprises a rectangular frame 11 and thin metal sheet 1 supported by the frame and provided with a plurality of small perforations for passing an electrom beam.
  • the shadow mask 10 is positioned in front of a face plate having a coating of phosphor 3 applied on the inner surface of the face plate.
  • a potentail for post-deflection focusing is impressed across the shadow mask 10 and the phospher or fluorescent screen 3 a strong electric field is created between the shadow mask 10 and electrodes (not shown) disposed close thereto, so that the electron beam impinges upon the shadow mask through a passage a or b will be reflected by the shadow mask 10 or causes it to emit secondary electrons.
  • a shadow mask for use in a colour picture tube of the type including a plurality of perforations for passing an electron beam characterized in that the layers of a substance capable of suppressing the emission of secondary electrons caused by the collision of the electron beam are formed on the opposite surfaces of the shadow mask. Such a layer can also formed on the inner wall of the perforation.
  • FIG. 1 is a diagrammatic plan view, partly broken away, of a shadow mask
  • FIG. 2 is an enlarged sectional view of a portion of a conventional shadow mask to explain the emission of secondary electrons caused by the impingement of electron beams;
  • FIG. 3 shows an enlarged sectional view of a portion of a shadow mask embodying the invention
  • FIG. 4 is a view similar to FIG. 4 but illustrating a modified embodiment of this invention.
  • graphite is coated on the front side 4 facing to the electron gun, not shown, and the rear side 5 facing to the fluorescent screen 3 (see FIG. 2) of a metal plate 1 of a shadow mask 10 by any well-known method to form layers of graphite 6 and 7, each having a thickness of from 3 to 20 microns.
  • the layer 6 on the front side prevents the secondary electron emission caused by an electron beam a which impinges directly upon layer 6, and the layer 7 on the rear side also prevents the secondary electron emission caused by an electron beam c which impinges upon the fluorescent screen and reflected thereby or the secondary electrons emitted by the collision of such electron beam c.
  • the graphite coating is also applied onto the inner wall of the perforation of the shadow mask.
  • the perforation 2 of the shadow mask is generally not cylindrical but generally consists of a first cup shaped section 21 having a smaller diameter on-the front side and a second cup shaped section 22 having a larger diameter on the rear side, the diameter of the second section being largest on the rear surface 5.
  • a graphite coating 8 is formed also on the inner surface of the large cup shaped section to a thickness of from 3 to 20 microns, for example, thereby preventing the secondary electron emission caused by the collision of an electron beam such as b.
  • a shadow mask for use in a colour picture tube of the type including a plurality of perforations for passing an electrom beam to a colour screen
  • the improvement which comprises low electron emissive layers of a substance coated on said shadow mask, said substance capable of suppressing the emission of secondary electrons caused by the collision of the electron beam with said mask directly or as reflected from said also applied on the inner surface of said second cup shaped section.

Landscapes

  • Electrodes For Cathode-Ray Tubes (AREA)
  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
US00214551A 1971-12-30 1972-01-03 Shadow masks for use in colour picture tubes Expired - Lifetime US3760214A (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB6085671 1971-12-30
DE2165703A DE2165703A1 (de) 1971-12-30 1971-12-30 Lochmasken fuer farbbildroehren
FR7147457A FR2166562A5 (enrdf_load_stackoverflow) 1971-12-30 1971-12-30
US21455172A 1972-01-03 1972-01-03

Publications (1)

Publication Number Publication Date
US3760214A true US3760214A (en) 1973-09-18

Family

ID=27431381

Family Applications (1)

Application Number Title Priority Date Filing Date
US00214551A Expired - Lifetime US3760214A (en) 1971-12-30 1972-01-03 Shadow masks for use in colour picture tubes

Country Status (4)

Country Link
US (1) US3760214A (enrdf_load_stackoverflow)
DE (1) DE2165703A1 (enrdf_load_stackoverflow)
FR (1) FR2166562A5 (enrdf_load_stackoverflow)
GB (1) GB1323620A (enrdf_load_stackoverflow)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3883770A (en) * 1972-01-19 1975-05-13 Hitachi Ltd Colour picture tubes
US4168450A (en) * 1976-07-19 1979-09-18 Hitachi, Ltd. Slot type shadow mask
US4422005A (en) * 1980-07-09 1983-12-20 U.S. Philips Corporation Channel plate electron multiplier
US4544860A (en) * 1981-10-19 1985-10-01 U.S. Philips Corporation Laminated channel plate electron multiplier
US4665338A (en) * 1983-05-17 1987-05-12 Kabushiki Kaisha Toshiba Front end elements for a color cathode ray tube
US4692659A (en) * 1985-03-27 1987-09-08 Kabushiki Kaisha Toshiba Color cathode ray tube having shadow mask with silicon
US4734615A (en) * 1985-07-17 1988-03-29 Kabushiki Kaisha Toshiba Color cathode ray tube
US6717342B2 (en) * 2000-08-29 2004-04-06 Lg Electronics Inc. Shadow mask in color CRT

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2728008A (en) * 1953-04-21 1955-12-20 Rca Corp Color-kinescopes, etc.
US2908838A (en) * 1957-02-25 1959-10-13 Corning Glass Works Aperture mask treatment to prevent cathode poisoning
US2942130A (en) * 1957-02-25 1960-06-21 Corning Glass Works Aperture mask coating to prevent cathode poisoning
US2971117A (en) * 1956-03-01 1961-02-07 Rca Corp Color-kinescopes, etc.
US3136916A (en) * 1961-05-17 1964-06-09 Gen Electric Image orthicon tube having specially coated decelerating field electrode
US3398309A (en) * 1966-08-10 1968-08-20 Rauland Corp Post-deflection-focus cathoderay tube
US3555334A (en) * 1967-11-03 1971-01-12 Philips Corp Cathode with graphite end shields

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2728008A (en) * 1953-04-21 1955-12-20 Rca Corp Color-kinescopes, etc.
US2971117A (en) * 1956-03-01 1961-02-07 Rca Corp Color-kinescopes, etc.
US2908838A (en) * 1957-02-25 1959-10-13 Corning Glass Works Aperture mask treatment to prevent cathode poisoning
US2942130A (en) * 1957-02-25 1960-06-21 Corning Glass Works Aperture mask coating to prevent cathode poisoning
US3136916A (en) * 1961-05-17 1964-06-09 Gen Electric Image orthicon tube having specially coated decelerating field electrode
US3398309A (en) * 1966-08-10 1968-08-20 Rauland Corp Post-deflection-focus cathoderay tube
US3555334A (en) * 1967-11-03 1971-01-12 Philips Corp Cathode with graphite end shields

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3883770A (en) * 1972-01-19 1975-05-13 Hitachi Ltd Colour picture tubes
US4168450A (en) * 1976-07-19 1979-09-18 Hitachi, Ltd. Slot type shadow mask
US4422005A (en) * 1980-07-09 1983-12-20 U.S. Philips Corporation Channel plate electron multiplier
US4544860A (en) * 1981-10-19 1985-10-01 U.S. Philips Corporation Laminated channel plate electron multiplier
US4665338A (en) * 1983-05-17 1987-05-12 Kabushiki Kaisha Toshiba Front end elements for a color cathode ray tube
US4692659A (en) * 1985-03-27 1987-09-08 Kabushiki Kaisha Toshiba Color cathode ray tube having shadow mask with silicon
US4734615A (en) * 1985-07-17 1988-03-29 Kabushiki Kaisha Toshiba Color cathode ray tube
EP0209346A3 (en) * 1985-07-17 1988-11-17 Kabushiki Kaisha Toshiba Colour cathode ray tube
US6717342B2 (en) * 2000-08-29 2004-04-06 Lg Electronics Inc. Shadow mask in color CRT

Also Published As

Publication number Publication date
DE2165703A1 (de) 1973-07-12
GB1323620A (en) 1973-07-18
FR2166562A5 (enrdf_load_stackoverflow) 1973-08-17

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